1. Field of the Invention
The present invention relates to an optical pickup device and an optical disk apparatus into which the optical pickup device is incorporated, particularly to a compatible type optical pickup device sorting a laser beam emitted from a common light source into two objective lenses and an optical disk apparatus into which the optical pickup device is incorporated.
2. Description of the Related Art
Currently, there are two optical disks, i.e., BD (Blu-ray Disc) and HDDVD (High-Definition Digital Versatile Disc), in which a laser beam having a blue wavelength is used. Because BD and HDDVD differ from each other in a thickness of a cover layer, two objective lenses compatible with BD and HDDVD are provided in the optical pickup device compatible with both BD and HDDVD, and the laser beam having the blue wavelength emitted from one semiconductor laser is sorted into the objective lenses by an optical system respectively.
A liquid crystal cell and a polarization beam splitter can be used as a configuration in which the laser beam is sorted into the two objective lenses. In the configuration, a polarization direction of the laser beam is changed into one of P-polarized light and S-polarized light with respect to the polarization beam splitter by the liquid crystal cell. In the case of P-polarized light, the laser beam is transmitted through the polarization beam splitter and guided to a first objective lens. In the case of the S-polarized light, the laser beam is reflected by the polarization beam splitter and guided to the first objective lens.
However, in the configuration, cost of the optical pickup device is increased because the liquid crystal cell is used as a function for sorting the laser beam into the two objective lenses Unfortunately, a problem arises that the laser beam strength is attenuated when the laser beam passes through the liquid crystal cell. Additionally, it is necessary that circuits and configurations for controlling drive of the liquid crystal cell be separately provided to guide the laser beam to which objective lens.